HOW DRM handles skywave propagation (digital radio mondiale)
This is copied directly from the DRM User Guide:
"For ionospheric propagation, the most severe Doppler spread is observed in the case of Near Vertical Incidence Sky-wave (NVIS) propagation. Because the path lengths between transmitter and receiver are quite short for NVIS, the distances between the ionospheric layers represent a larger proportion of the total path length. The several reflections can also have similar energy levels. This gives rise to significant values of Doppler spread. "To counter the effects of Doppler shift and Doppler spread the frequency separation between the OFDM carriers in the DRM signal is progressively increased (e.g. the carrier spacing in Mode D is more than 2.5 times that in Mode A). This ensures that the frequency spread experienced is kept to a sufficiently small fraction of the carrier spacing to allow correct demodulation." |
HOW DRM handles skywave propagation (digital radio mondiale)
On Oct 1, 1:42 pm, Ratata wrote:
wrote: "To counter the effects of Doppler shift and Doppler spread the frequency separation between the OFDM carriers in the DRM signal is progressively increased (e.g. the carrier spacing in Mode D is more than 2.5 times that in Mode A). This ensures that the frequency spread experienced is kept to a sufficiently small fraction of the carrier spacing to allow correct demodulation." better than IBOC ?? Digital Radio Mondiale *is* IBOC. (Like HD Radio, it sits right next- door to the AM signal, widening the channel by a few more kilohertz) |
HOW DRM handles skywave propagation (digital radio mondiale)
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HOW DRM handles skywave propagation (digital radio mondiale)
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DRM -Ain't- IBOC
On Oct 2, 4:26 am, wrote:
On Oct 1, 1:42 pm, Ratata wrote: wrote: "To counter the effects of Doppler shift and Doppler spread the frequency separation between the OFDM carriers in the DRM signal is progressively increased (e.g. the carrier spacing in Mode D is more than 2.5 times that in Mode A). This ensures that the frequency spread experienced is kept to a sufficiently small fraction of the carrier spacing to allow correct demodulation." better than IBOC ?? - Digital Radio Mondiale *is* IBOC. (Like HD Radio, it sits right next- - door to the AM signal, widening the channel by a few more kilohertz) SFTV -aka- "Hybrid Digital" Man, DOH ! - You had beeter go back and re-do your DRM 101 and IBOC 101 Classes again. ~ RHF Digital Radio Mondiale (DRM) http://en.wikipedia.org/wiki/Digital_Radio_Mondiale Unique Digital Broadcast Signal Mode {Non-Analog AM} In-Band On-Channel (IBOC) so called "HD" Radio http://en.wikipedia.org/wiki/IBOC Combined Analog and Digital Broadcast Signal Modes http://en.wikipedia.org/wiki/HD_Radio DRM is All Digital Mode of Shortwave (HF) Radio Transmission http://www.eiinfo.fh-konstanz.de/dow...rm/image35.jpg DRM Digital Signal at 13,790 kHz with AM Analog http://shortwaveradio.org/drm_13_Af_010511_2100.jpg Signals at 13770 kHz; 13800 kHz; and 13810 kHz. * Clearly you can see that DRM requires at least 15 kHz of Channel "Spacing" for it not to interfere with any 'adjacent' DRM or Analog Radio Broadcast. Note - That the DRM Shortwave Radio Broadcasts are independent and separate from the older Analog "AM" Radio Transmission Mode Broadcasts. * International, National and Local DRM Broadcasts Underway in Markets Worldwide http://www.drm.org/livebroadcast/livebroadcast.php From what I have read and heard DRM appears to work best as a Directed Beam Radio {Audio} Delivery System up to 1000 Miles and out to 2500 Miles. * DRM Tropical Band {With-In-Country} Omni-Directional Radio Broadcasting best up to 300 Miles and out to 1000 Miles. Analog "AM" And DRM Can Not Co-Exist On The Same Channel {Frequency} At The Same Time [.] As with all Shortwave Radio Broadcasting the Coordinated Scheduling of Broadcast Time and Frequency is important for DRM Broadcasters since they take up Four Times (4X) the Bandwidth as the Analog "AM" Broadcasters. High Frequency Co-ordination Conference (HFCC) HFCC = http://www.hfcc.org/ drm ain't iboc -and- iboc ain't drm ~ RHF |
DRM -Ain't- IBOC
On Oct 2, 6:17 pm, RHF wrote:
drm ain't iboc -and- iboc ain't drm ~ RHF . You are dumb. DRM has a hybrid digital/analog mode. See this manual, page 20. Notice how the DRM sits "in-band on-channel" same as the HD Radio works. www.drm.org/pdfs/Broadcast_Manual.pdf |
DRM -Ain't- IBOC
THIS DISCUSSION IS OFF-TOPIC FOR REC.AUDIO.TECH
(AND REC.AUDIO.CAR, FOR THAT MATTER) PLEASE DROP REC.AUDIO.TECH FROM THIS DISCUSSION |
DRM -Ain't- IBOC
On Oct 3, 5:02 am, wrote:
On Oct 2, 6:17 pm, RHF wrote: drm ain't iboc -and- iboc ain't drm ~ RHF . - You are dumb. DRM has a hybrid digital/analog mode. - See this manual, page 20. Notice how the DRM sits - "in-band on-channel" same as the HD Radio works. - - www.drm.org/pdfs/Broadcast_Manual.pdf yo, Yo. YO ! - SFTV - Dumb I May Be . . . But presenetly the majority of DRM Broadcasting on the Shortwave Radios is Pure {100%} DRM "Digital" and it Trashes 20 kHz of Bandwidth around it and makes good old AM Analog Shortwave Broadcasting very hard to Hear. SFTV - Your Such A Gooder "Hybrid Digital" Man ! ~ RHF |
DRM -Ain't- IBOC
wrote
On Oct 2, 6:17 pm, RHF wrote: drm ain't iboc -and- iboc ain't drm ~ RHF You are dumb. DRM has a hybrid digital/analog mode. See this manual, page 20. Notice how the DRM sits "in-band on-channel" same as the HD Radio works. www.drm.org/pdfs/Broadcast_Manual.pdf No, the manual does not state "DRM has a hybrid digital/analog mode". A simulcast is not necessarily hybrid. I also cannot find any affirmation on your statement Notice how the DRM sits "in-band on-channel". RHF dumb? Don't think so. Take a good look on that page 20 of the manual. [quote] DRM supports a number of different simulcast options. Currently the supported simulcast modes require the use of additional spectrum outside an assigned 9 or 10 kHz channel (Multi-Channel or Multi-frequency Simulcast, MCS). The DRM signal can be located in the next adjacent upper or lower channel and can occupy a half or whole channel depending on the bandwidth option chosen. [unquote] So far nothing about IBOC. In general, a simulcast is a simultaneous transmission of the same programme. Here, both transmissions are located in two adjacent channels, the DRM transmitter operating with less power than the analogue signal transmitter. [quote] (..) a satisfactory compromise can be obtained when the DRM power level is around 14-16 dB below the adjacent analogue signal. [unquote] Unfortunately, operating on two adjacent frequencies (channels) may give rise to interference problems. With IBOC no such problems would occur, isn't it? Now read the following about a possible DRM-future... [quote] In an ideal world it would also be possible to transmit both an analogue and a digital signal within the same channel (9 or 10 kHz) so that the analogue service could be received, without interference from the digital signal, on any analogue receiver. [unquote] With only one transmission there would be no interference, so in the real world anno 2007 interference may arise and DRM is not IBOC. The statement "DRM is not IBOC" is also apparent from some other quotes from page 20: [quote] (..) promising proposals for a SCS (Single Channel Simulcast) option are currently being evaluated (..) Even if single channel simulcast may prove a difficult goal to achieve (..) [unquote] DRM is not IBOC, correct me if I'm wrong. gr, Hein |
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